Remove old, dead compat code.

We no longer need to od these things conditionally, and the fallbacks
are to 4.2BSD era defaults, which nobody uses anymore. Vixie cron has
diverged from upstream anyway in our tree, and it's not clear there's
actually a viable upstream anymore. Plus, we don't follow the
vendor-supplied code pattern here.

I'm doing this to reduce false positives from grep.

usr.sbin/cron/cron/pathnames.h

@@ -53,11 +53,7 @@
 
 			/* where should the daemon stick its PID?
 			 */
-#ifdef _PATH_VARRUN
-# define PIDDIR	_PATH_VARRUN
-#else
-# define PIDDIR "/etc/"
-#endif
+#define PIDDIR	_PATH_VARRUN
 #define PIDFILE		"%scron.pid"
 
 			/* 4.3BSD-style crontab */
@@ -68,16 +64,4 @@
 			/* what editor to use if no EDITOR or VISUAL
 			 * environment variable specified.
 			 */
-#if defined(_PATH_VI)
-# define EDITOR _PATH_VI
-#else
-# define EDITOR "/usr/ucb/vi"
-#endif
-
-#ifndef _PATH_BSHELL
-# define _PATH_BSHELL "/bin/sh"
-#endif
-
-#ifndef _PATH_DEFPATH
-# define _PATH_DEFPATH "/usr/bin:/bin"
-#endif
+#define EDITOR _PATH_VI